EFFECT OF CONJUGATION 323 



of such necessary replacements will give a comparative meas- 

 ure of the mortality in the two sets. In the non-conjugants D 

 (slide series) there were necessary 34 such replacements; in the 

 conjugant progeny A' (watch glass series), there were 22, Of the 

 conjugant line (K) six lived to the end (21 days), the average 

 number of fissions for these being 21. Of the non-conjugant 

 lines {D), four were alive at the end, their average number of 

 fissions being 16.25. On the sixteenth of July ten lines were 

 alive in each set; the average number of fissions at that time was 

 for the conjugants {K) 15.6; for the non-conjugants (Z)), 13.00. 



Experiment 11 f. On July 16, an additional comparison was 

 made, taking fourteen each of the conjugants {K) and non- 

 conjugants iD). In the nature of the results this experiment 

 lasted but a short time. Of the non-conjugants D (slide series), 

 only two di\'ided, and all were dead by the third day. Among 

 the conjugants (iv), all divided; three died out during the three 

 days; the remaining 10 averaged six fissions in three days. The 

 non-conjugants (Z>) are clearly depressed and weak. 



Experiment 11 g. A crucial question is whether the two sets 

 of non-conjugants of unlike history — the slide series D and the 

 watch glass series H — are still unlike in their vigor, as comparison 

 with the conjugants (Experiments 11 a-f) indicates. Therefore, 

 on July 16 comparative tests were made of these two, and also 

 of the progeny of the conjugants of June 3 {K). 



The three lines compared are those designated D, K, and H, 

 figure 2. Of line D (non-conjugants cultivated on slides up to 

 June 7) two watch glasses, containing five specimens each, were 

 taken. Of the other non-conjugant line H (cultivated in watch 

 glasses since May 15), the same number was propagated, in the 

 same way. Of the ex-conjugants of June 3 — the line K, with 

 the same cultural history as the non-conjugants of line H — three 

 watch glasses of five specimens each were propagated. In all 

 three series the conditions were made exactly alike, all the animals 

 being washed in the same water before they were introduced into 

 the culture fluid. At intervals of some days the animals were 

 removed one by one to a new watch glass, counted, and the 

 number reduced, so as to be the same in all. The ratio of those 



